check_PR_source_branch.yml

name: Check Source Branch

on:
  pull_request_target:

jobs:
  check-branches:
    name: Check branches
    runs-on: ubuntu-latest
    steps:
      - name: Check branches
        env:
          HEAD_REF: ${{ github.head_ref }}
          BASE_REF: ${{ github.base_ref }}
          ENVIRONMENT: ${{ github.event.pull_request.head.repo.full_name != github.repository && 'external' || 'internal' }}
        run: |
          if [[ "$ENVIRONMENT" == "internal" ]] && [[ "$HEAD_REF" != "dev" ]] && [[ "$BASE_REF" == "main" ]]; then
              echo "Merge requests to the main branch are only allowed from the dev branch."
              exit 1
          fi

          if [[ "$ENVIRONMENT" == "external" ]] && [[ "$BASE_REF" != "dev" ]]; then
              echo "Merge requests from external repositories are only allowed to the dev branch."
              exit 1
          fi